.TH LUT5 "9" "2020-08-11" "LinuxCNC Documentation" "HAL Component"
.de TQ
.br
.ns
.TP \\$1
..

.SH NAME

lut5 \- Arbitrary 5-input logic function based on a look-up table
.SH SYNOPSIS
.HP
.B loadrt lut5 [count=\fIN\fB|names=\fIname1\fB[,\fIname2...\fB]]
.SH DESCRIPTION


.B lut5
constructs a logic function with up to 5 inputs using a
\fBl\fRook-\fBu\fRp \fBt\fRable. The value for \fBfunction\fR can be
determined by writing the truth table, and computing the sum of \fBall\fR
the \fBweights\fR for which the output value would be \fRTRUE\fR.
The weights are hexadecimal not decimal so hexadecimal math must be used to
sum the weights. A wiki page has a calculator to assist in computing the proper
value for function.
.PP
http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Lut5
.PP
Note that LUT5 will generate any of the 4,294,967,296
logical functions of 5 inputs so \fBAND\fR, \fBOR\fR, \fBNAND\fR,
\fBNOR\fR, \fBXOR\fR and every other combinatorial function is possible.
.PP
.SS Example Functions
A 5-input
\fIand\fR function is TRUE only when all the inputs are true, so the correct
value for \fBfunction\fR is \fB0x80000000\fR.
.PP
A 2-input \fIor\fR function would be the sum of \fB0x2\fR + \fB0x4\fR +
\fB0x8\fR, so the correct value for \fBfunction\fR is \fB0xe\fR.
.PP
A 5-input \fIor\fR
function is TRUE whenever any of the inputs are true, so the correct value for
\fBfunction\fR is \fB0xfffffffe\fR. Because every weight except \fB0x1\fR
is true the function is the sum of every line except the first one.
.PP
A 2-input \fIxor\fR function is
TRUE whenever exactly one of the inputs is true, so the correct value for
\fBfunction\fR is \fB0x6\fR.  Only \fBin-0\fR and \fBin-1\fR should be
connected to signals, because if any other bit is \fBTRUE\fR then the output
will be \fBFALSE\fR.
.PP
.ie '\*[.T]'html' \{\
.HTML \
<STYLE> \
#weight TD { text-align: center; padding-left: .5ex; padding-right: .5ex } \
#weight TH { text-align: center; padding-left: .5ex; padding-right: .5ex } \
#weight TD.W { text-align: right; } \
</STYLE> \
<TABLE ID="weight" STYLE="border: 1px solid black; border-collapse: collapse"> \
    <COL SPAN=5 STYLE="margin: .2ex"><COL SPAN=1 STYLE="border-left: 1px solid black"> \
<TR STYLE="border-bottom: 1px solid black"> \
    <TH COLSPAN=6>Weights for each line of truth table \
<TR STYLE="border-bottom: 1px solid black"> \
    <TH>Bit 4<TH>Bit 3<TH>Bit 2<TH>Bit 1<TH>Bit 0<TH> Weight \
<TR><TD>0<TD>0<TD>0<TD>0<TD>0<TD CLASS="w">0x1 \
<TR><TD>0<TD>0<TD>0<TD>0<TD>1<TD CLASS="w">0x2 \
<TR><TD>0<TD>0<TD>0<TD>1<TD>0<TD CLASS="w">0x4 \
<TR><TD>0<TD>0<TD>0<TD>1<TD>1<TD CLASS="w">0x8 \
<TR><TD>0<TD>0<TD>1<TD>0<TD>0<TD CLASS="w">0x10 \
<TR><TD>0<TD>0<TD>1<TD>0<TD>1<TD CLASS="w">0x20 \
<TR><TD>0<TD>0<TD>1<TD>1<TD>0<TD CLASS="w">0x40 \
<TR><TD>0<TD>0<TD>1<TD>1<TD>1<TD CLASS="w">0x80 \
<TR><TD>0<TD>1<TD>0<TD>0<TD>0<TD CLASS="w">0x100 \
<TR><TD>0<TD>1<TD>0<TD>0<TD>1<TD CLASS="w">0x200 \
<TR><TD>0<TD>1<TD>0<TD>1<TD>0<TD CLASS="w">0x400 \
<TR><TD>0<TD>1<TD>0<TD>1<TD>1<TD CLASS="w">0x800 \
<TR><TD>0<TD>1<TD>1<TD>0<TD>0<TD CLASS="w">0x1000 \
<TR><TD>0<TD>1<TD>1<TD>0<TD>1<TD CLASS="w">0x2000 \
<TR><TD>0<TD>1<TD>1<TD>1<TD>0<TD CLASS="w">0x4000 \
<TR><TD>0<TD>1<TD>1<TD>1<TD>1<TD CLASS="w">0x8000 \
<TR><TD>1<TD>0<TD>0<TD>0<TD>0<TD CLASS="w">0x10000 \
<TR><TD>1<TD>0<TD>0<TD>0<TD>1<TD CLASS="w">0x20000 \
<TR><TD>1<TD>0<TD>0<TD>1<TD>0<TD CLASS="w">0x40000 \
<TR><TD>1<TD>0<TD>0<TD>1<TD>1<TD CLASS="w">0x80000 \
<TR><TD>1<TD>0<TD>1<TD>0<TD>0<TD CLASS="w">0x100000 \
<TR><TD>1<TD>0<TD>1<TD>0<TD>1<TD CLASS="w">0x200000 \
<TR><TD>1<TD>0<TD>1<TD>1<TD>0<TD CLASS="w">0x400000 \
<TR><TD>1<TD>0<TD>1<TD>1<TD>1<TD CLASS="w">0x800000 \
<TR><TD>1<TD>1<TD>0<TD>0<TD>0<TD CLASS="w">0x1000000 \
<TR><TD>1<TD>1<TD>0<TD>0<TD>1<TD CLASS="w">0x2000000 \
<TR><TD>1<TD>1<TD>0<TD>1<TD>0<TD CLASS="w">0x4000000 \
<TR><TD>1<TD>1<TD>0<TD>1<TD>1<TD CLASS="w">0x8000000 \
<TR><TD>1<TD>1<TD>1<TD>0<TD>0<TD CLASS="w">0x10000000 \
<TR><TD>1<TD>1<TD>1<TD>0<TD>1<TD CLASS="w">0x20000000 \
<TR><TD>1<TD>1<TD>1<TD>1<TD>0<TD CLASS="w">0x40000000 \
<TR><TD>1<TD>1<TD>1<TD>1<TD>1<TD CLASS="w">0x80000000 \
</TABLE>
\}
.el \{\
.TS
box tab(;);
cb s s s s s
cb cb cb cb cb | cb
c  c  c  c  c  | r.
Weights for each line of truth table
_
Bit 4;Bit 3;Bit 2;Bit 1;Bit 0; Weight
_
0;0;0;0;0;0x1
0;0;0;0;1;0x2
0;0;0;1;0;0x4
0;0;0;1;1;0x8
0;0;1;0;0;0x10
0;0;1;0;1;0x20
0;0;1;1;0;0x40
0;0;1;1;1;0x80
0;1;0;0;0;0x100
0;1;0;0;1;0x200
0;1;0;1;0;0x400
0;1;0;1;1;0x800
0;1;1;0;0;0x1000
0;1;1;0;1;0x2000
0;1;1;1;0;0x4000
0;1;1;1;1;0x8000
1;0;0;0;0;0x10000
1;0;0;0;1;0x20000
1;0;0;1;0;0x40000
1;0;0;1;1;0x80000
1;0;1;0;0;0x100000
1;0;1;0;1;0x200000
1;0;1;1;0;0x400000
1;0;1;1;1;0x800000
1;1;0;0;0;0x1000000
1;1;0;0;1;0x2000000
1;1;0;1;0;0x4000000
1;1;0;1;1;0x8000000
1;1;1;0;0;0x10000000
1;1;1;0;1;0x20000000
1;1;1;1;0;0x40000000
1;1;1;1;1;0x80000000
.TE
\}

.SH FUNCTIONS
.TP
\fBlut5.\fIN\fB\fR

.SH PINS
.TP
.B lut5.\fIN\fB.in-0\fR bit in \fR
.TQ
.B lut5.\fIN\fB.in-1\fR bit in \fR
.TQ
.B lut5.\fIN\fB.in-2\fR bit in \fR
.TQ
.B lut5.\fIN\fB.in-3\fR bit in \fR
.TQ
.B lut5.\fIN\fB.in-4\fR bit in \fR
.TQ
.B lut5.\fIN\fB.out\fR bit out \fR
.SH PARAMETERS
.TP
.B lut5.\fIN\fB.function\fR u32 rw \fR
.SH LICENSE

GPL
